If your CNAME is set up, but your site doesn't load without www, you need to check that your A records are correct and then recreate the SSL certificate.
To check if A records are correct:
Go to whatsmydns.net.
Change the search to A.
Enter the base domain and click Search.
Check that both IP addresses are showing (35.172.94.1 and 100.24.208.97).
If the correct IP addresses are not showing, go to your DNS settings and update the A records to:
First A record.35.172.94.1
Second A record.100.24.208.97
If there is an additional IP address that is not from Duda, the SSL certificate cannot be generated. To fix this, go to your domain settings and remove the extra A record. Most domain hosts have instructions on creating and removing A records in their help center. For a list of common domain hosts and their help information, see Specific Domain Host Records. If you still need help with your A record, contact your domain host.
After updating your A records you will need to recreate the SSL certificate.
To recreate the SSL certificate:
Click Settings, and then click the Site SSL tab.
Click Recreate Certificate.
You will need to wait for the certificate to be recreated.
Adding AAAA and CAA records prevents issuing an SSL certificate. Please ensure you do not have these records configured.